They’re actually quite different sorts of schools, so I think a lot depends on what sort of environment and senior-school route you’re after.
Dulwich Cranbrook isn’t really a traditional 13+ prep in the classic sense, partly because it goes through to 16. Quite a lot of children either stay there or move into the local grammar system, particularly Cranbrook, so it doesn’t have quite the same culture of feeding the major public schools at 13.
Saint Ronan’s is much more of a traditional country prep. Some do leave for Cranbrook at 11, but it’s fundamentally geared towards 13+ senior-school entry and the more traditional independent-school route. King’s Canterbury is a common destination, but children also often go on to Tonbridge, Sevenoaks, Brighton College, Marlborough, Harrow, Radley, Charterhouse and others. Benenden is also a notably common destination for girls, both day and boarding.
Saint Ronan’s has also always had quite a multigenerational feel. Former pupils often send their own children there and, historically, many Old Ronians went on to Eton, so there have long been strong links between the two schools. The parent body has also traditionally tended to come from more established independent-school backgrounds.
Music is a particular strength at Saint Ronan’s. There’s a strong culture of choirs, ensembles, individual tuition and performance, and a good number of children leave with music awards or scholarships. Sport is also a big part of school life, but it doesn’t feel especially results-driven.
The atmosphere is quite distinctive too. Saint Ronan’s is very much in the Cottesmore/Brambletye/Port Regis mould, a traditional country prep school, characterful and with a strong identity.
Dulwich just has a different feel really. It’s less rooted in the traditional 13+ prep-school model and more of an all-through independent school, with more children either staying on or moving into the local grammar system.
So I think that’s the main difference. If you’re already thinking in terms of Eton, Tonbridge, Wycombe Abbey, Sevenoaks, Brighton, Saint Ronan’s sits much more naturally in that traditional 13+ prep-school world. Dulwich has a different structure and a different destination profile.